Effects On The Ca²⁺ Of Root Cells And Mesophyll Of Wheat Seedlings Exposed To Enhanced Ultraviolet-b Radiation And The Reparation Role By Irradiated He-Ne Laser

In this paper, 'Jinmai No.47' wheat(Triticum aestivum)as research material, and the seedlings of wheat were exposed to He-Ne laser irradiation (5mW·mm-2)and enhanced UV-B radiation(10.08kJ·m-2·d-1). The fluorescence features of intracellular calcium distribution were studied and the cytoplasmic free calcium ion concentration was measured by the laser scanning confocal Microtechnique when Fluorescent probe Fluo-3/AM was loaded into the protoplast of the wheat mesophyll cells or the wheat roots cells under low temperature. The contents of calmodulin were measured after extracted the calmodulin. In order to explore the effects of the calcium signal in the calcium signaling pathway when the seedlings of wheat were exposed to enhanced UV-B radiation. The results were showed as follows:(1)The fluorescence features of intracellular calcium distribution were studied when fluorescent probe-fluo-3/AM was loaded into the wheat root cells. The results showed that the fluorescence of calcium is mainly distributed in the peripheral cytoplasm when the wheat without treatment. And the fluorescence of intracellular calcium not only distributed in the peripheral cytoplasm, and it also can be observed in the cytoplasm between cell wall and cell membrane when the wheat was treated with UV-B radiation.(2)After measured the fluorescence intensity of intracellular calcium of single cell,we found that the cytoplasmic free calcium ion concentration increased significantly on the UV-B treated group.(3)The fluorescence features of intracellular calcium distribution were studied by the laser scanning confocal Microtechnique when Fluorescent probe Fluo-3/AM was loaded into the protoplast of the wheat mesophyll cells. The results showed that the fluorescence of cytoplasmic calcium ion distributed uniformly and mainly in plasma membrane or around the nucleus-in control group(CK). The distribution of fluorescence in UV-B radiation group was similar with CK,but protoplast surface was not smooth.(4) After measured the cytosolic calcium ion concentration, we found that the fluorescence intensity of UV-B radiation group is higher than control group.The strength of fluorescence intensity can be directed reflects the concentration of the calcium ion. It demonstrated that the wheat mesophyll cells maintain a high level of concentration of calcium ions in enhanced UV-B radiation group.(5)The extracted calmodulin were detected through SDS-PAGE eletrophoresis and the results were showed there exists a protein band between the 14.4kp and 20.1 kp band. We speculated it as calmodulin and determined its molecular weight is 16.245 by gel analysis.(6)The calmodulin contents was determined by the Bradford method.The results showed that the He-Ne laser and enhanced UV-B radiation can also increase the contents of the calmodulin obviously. It demonstrated that the calcium ion concentration changes firstly when enhanced UV-B radiation.Then the target proteins of calcium ion-calmodulin changes. It is suggested that the Ca2+ signals be involved in the process which wheat response to the stress of UV-B radiation by a certain way.